The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
(1) Field of the Invention
The present invention generally relates to a method and system for determining the velocity of a moving body, and more particularly to a method and system for determining the linear and angular velocity of a moving body using the Barkhausen effect.
(2) Description of the Prior Art
Magnetic sensors are commonly used in determining the velocity of moving bodies. Some of the conventional sensors typically used today are Hall Effect sensors, fluxgate sensors, magnetoresistive sensors, magnetostrictive sensors, magnetoinductive sensors and SQUID sensors. However, these devices have several disadvantages. For example, the SQUID sensor can only operate properly at superconductive temperatures. The flip coil magnetometer utilizes moving parts thereby creating problems associated with component malfunction and replacement. Hall Effect sensors, fluxgate sensors, magnetoresistive sensors, magnetostrictive sensors, magnetoinductive sensors all require an external bias or bridge-type circuit for proper operation. What is needed is a sensor that is a passive device and which can operate at room temperature. A further desired feature is that it must be simple in construction in order to reduce the costs related to manufacturing, maintenance and repair.
Therefore, it is an object of the present invention to provide a system and method for measuring the velocity of a moving body that does not exhibit or present the problems and disadvantages of conventional sensors.
It is another object of the present invention to provide a passive system for measuring the velocity of a moving body.
It is a further object of the present invention to provide a system for measuring the velocity of a moving body that can operate at room temperature.
It is yet another object of the present invention to provide a system for measuring the velocity of a moving body that is relatively less complex in design and construction than conventional systems.
Other objects and advantages of the present invention will be apparent to one of ordinary skill in the art in light of the ensuing description of the present invention.
The present invention is directed to a method and system for determining the rotational (or angular) or linear velocity of a moving body. The system utilizes a Barkhausen Effect magnetic field sensor. In one embodiment, the Barkhausen Effect magnetic field sensor comprises a coil wound about a silicon-steel core. In one embodiment, the coil comprises a predetermined number of turns of magnet wire. A permanent magnet is attached to the body whose motion is to be monitored in order to determine its velocity. As the body moves, the permanent magnet realigns small, atomic size magnetic domains in the silicon-steel core and, as a result of Faradays law, e.m.f. (electromotive force) impulses (also known as xe2x80x9cinductive kicksxe2x80x9d) are produced in the coil. As the velocity of the body increases, a plurality of e.m.f. impulses are created which define a distinct signal. This analog voltage is filtered, amplified and then converted into a digital signal. The digital signal is then fed into other signal processing circuitry that processes the signal to determine the velocity of the moving body.